Orlando - A Florida family scavenging for sunken treasure on a shipwreck has found the missing piece of a 300-year-old gold filigree necklace sacred to Spanish priests, officials said on Tuesday.Eric Schmitt, a professional salvager, was scavenging with his parents when he found the crumpled, square-shaped ornament on a leisure trip to hunt for artefacts in the wreckage of a convoy of 11 ships that sank in 1715 during a hurricane off central Florida's east coast.After the discovery last month, a team of Spanish historians realised the piece fit together with another artefact recovered 25 years ago. It formed an accessory called a pyx, worn on a chain around a high priest's neck to carry the communion host. The dollar value is uncertain."It's priceless, unique, one of a kind", said Brent Brisben, operations manager for Queens Jewels, which owns rights to the wreckage, located in 4.5m deep Atlantic Ocean waters.Schmitt, who lives near Orlando, last year discovered about $300 000 worth of gold coins and chains from the same wreckage, Brisben said. Schmitt's parents have hunted for sunken treasure as a hobby for a decade.By law, the treasure will be placed into the custody of the US District Court in South Florida, Brisben said. The state of Florida may take possession of up to 20% of the find. The rest will be split evenly between Brisben's company and the Schmitt family.